macmikeman, when you start talking close 50kVA, that's going to be dumping a significant heat load into the cavity and you have to start worrying about ventilation, too. A drop ceiling tends to trap hot air, so it's a little more difficult than just putting a few grilles in.
poorboy: to answer your question, as an engineer, there is very little difference between wall-mount, floor-mount or ceiling-mount. It depends on the size (if it's large, it's WAY easier to install on the ground), but moreso the cable routing and other practical reasons that factor more into the cost of the job than anything else. As transformers generate a lot of heat load, we usually like to place them in ventilated spaces vs air conditioned spaces so as to avoid the A/C costs.
And yes, everyone hates the hum- there are numerous reasons not to install transformers in office spaces. If the transformer was put there, it was probably just to shave a couple bucks.
[This message has been edited by SteveFehr (edited 11-01-2006).]
